The present invention relates to a system for mounting a pre-vaporizing bowl to the upstream end of a combustion chamber wall in a gas turbine engine.
Most present day gas turbine engines, particularly those turbojet engines designed for aircraft use, are equipped with annular combustion chambers extending around a longitudinal axis of the engine. Such engines also have a pre-vaporizing bowl around each fuel injection nozzle interposed between the nozzle and an upstream end wall of the combustion chamber. As is well known in the art, the pre-vaporizing bowls generate air turbulence around the point where the fuel is injected into the combustion chamber to optimize the vaporization of the fuel. Examples of such pre-vaporizing bowls may be found in the following U.S. Pat. Nos. 4,726,182; 4,696,157; and 4,754,600; as well as French Patent 2,585,770.
Since the combustion chamber walls are subjected to very high temperatures during operation of the gas turbine engine, they undergo a generally radial expansion when heated and a generally radial contraction when they are cooled. In order to accommodate the relative radial movement between the combustion chamber walls and the fuel injection nozzle, the pre-vaporizing bowl must be mounted between these elements in such a manner as to allow it to move relative to the combustion chamber wall. Typical examples of such mounting may be found in U.S. Pat. No. 4,322,955 as well as French Patents 1,547,843 and 2,479,952.
Today's turbojet engines are designed as a series of modules which are subsequently assembled to form the engine. The assembly sequence for the combustion chambers is usually accomplished by assembling the combustion chamber (fitted with its pre-vaporizing bowls) to a subassembly that has been equipped with the fuel injector nozzles. The assembly takes place while the engine is in a horizontal orientation and usually involves sliding the combustion chamber subassembly horizontally until it is mated with the subassembly having the fuel injection nozzles.
In this position, gravity urges the radially moveable pre-vaporizing bowls downwardly to a position wherein their centers are slightly eccentric with respect to the centers of the openings through the combustion chamber wall. As a result, the pre-vaporizing bowls may be misaligned with the fuel injection nozzle which presents the danger of damaging contact between the pre-vaporizing bowl and the fuel injection nozzle during the assembly process.